SULFUR K-EDGE XANES SPECTROSCOPY: CHEMICAL STATE AND CONTENT OF SULFUR IN SILICATE GLASSES
SULFUR K-EDGE XANES SPECTROSCOPY: CHEMICAL STATE AND CONTENT OF SULFUR IN SILICATE GLASSES
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硫 K 边 XANES 光谱：硅酸盐玻璃中硫的化学状态和含量
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发表时间：
2005
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通讯作者：
P. King
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作者：
M. Fleet;Xiaoyang Liu;S. Harmer;P. King
利用同步辐射S K边X射线吸收近边结构（XANES）光谱学，并使用能量选择荧光探测器，对东加拉帕戈斯裂谷的玄武质玻璃中硫的化学状态和局部环境以及实验室淬火实验进行了研究。我们还利用常规荧光产额和全电子产额（TEY）记录模式，研究了从1500°C淬火的6NaAlSiO4 - CaS - CaSO4体系中的熔体以及各种参考化合物中的硫。溶解在钠铝硅酸盐玻璃中的CaS的S K边XANES光谱在2475 eV附近以一个宽的单峰边缘特征为主，这与熔体中孤立的S⁻Ca配位多面体一致，而淬火的含CaSO4端元熔体的光谱则类似于结晶硫酸盐的XANES光谱。XANES相对面积与硫的重量百分比含量之间的线性相关性已被用于估算青金石样品（电子探针分析为5.6 - 6.3重量%）、方柱石族矿物（0.4重量%）和玄武质玻璃（0.04 - 0.15重量%）中的硫含量。在还原（WM和IQF固体氧缓冲）条件下合成的玄武质玻璃的S K边XANES光谱以2470 - 2482 eV处的一个宽吸收峰为主，同时在2470 - 2471 eV处有一个弱峰或肩峰，并且可以通过混合FeS和碱土单硫化物的XANES光谱来重现。东加拉帕戈斯裂谷玻璃的S K边XANES光谱也以S²⁻为主，但一个TEY光谱显示可能存在硫代硫酸盐，另一个则显示有微量硫酸盐。
The chemical state and local environment of sulfur in basaltic glasses from the eastern Galapagos rift and quenched laboratory experiments have been investigated by synchrotron-radiation S K-edge X-ray absorption near-edge structure (XANES) spectroscopy, using an energy-selective fl uorescence detector. We have also investigated sulfur in melts in the system 6NaAlSiO4–CaS– CaSO4 quenched from 1500°C and various reference compounds, using conventional fl uorescence yield and total-electron yield (TEY) recording modes. The S K-edge XANES spectrum of CaS dissolved in Na-aluminosilicate glass is dominated by a broad singlet edge-feature near 2475 eV, consistent with isolated SCan coordination polyhedra in the melt, whereas that of quenched end-member CaSO4-bearing melt is similar to XANES spectra of crystalline sulfates. The linear correlation between relative XANES area and wt% content of sulfur has been used to estimate the content of sulfur in samples of lazurite (5.6–6.3 wt% by EPMA), scapolite-group minerals (0.4 wt%) and the basaltic glasses (0.04–0.15 wt%). The S K-edge XANES spectra of basaltic glasses synthesized under reducing (WM and IQF solid oxygen-buffer) conditions are dominated by a single broad absorption peak at 2470–2482 eV in combination with a weak peak or shoulder at 2470–2471 eV, and are reproduced by mixing XANES spectra of FeS and alkaline-earth monosulfi des. The S K-edge XANES spectra for glasses from the eastern Galapagos rift are also dominated by S 2– , but one TEY spectrum shows possible thiosulfate and another, trace sulfate.